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AFCAT Numerical Ability · Profit and Loss

Marked Price, Discount and Successive Discounts

A discount is taken on the marked price and a profit on the cost price; successive discounts multiply, and a markup followed by a discount is one product of two multipliers.

Why this matters

Two bases meet on this page: the discount is on the marked price and the profit on the cost. One AFCAT past-year question, from 2016, asks for the cost from a marked price, a discount and a profit. Most lost marks come from adding successive discounts or taking a profit on the marked price.

Concept 1 of 4: Discount on the marked price

The marked price (MP), also called the list or label price, is the price on the tag. A discount is a percentage of the MP, and the customer pays the rest.

Definition

  • Discount =MP−SP= MP - SP; discount % =discountMP×100= \dfrac{\text{discount}}{MP} \times 100.
  • After a d%d\% discount, SP=MP(1−d100)SP = MP\left(1 - \tfrac{d}{100}\right), so MP=SP÷(1−d100)MP = SP \div \left(1 - \tfrac{d}{100}\right).
  • Two discounts compared on the same MP: the extra d%d\% is worth d%d\% of the MP.

Selling price after a discount

SP=MP(1−d100)SP = MP\left(1 - \dfrac{d}{100}\right)

Worked example

A jacket marked ₹2,400 is sold for ₹1,980. Find the discount per cent. At what price would a 20%20\% discount sell it?
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The same idea in a practice question:

Practice questionEasy

Example 1 · Profit and Loss · Marked Price and Discounts

A watch was sold for ₹1,440 after giving a discount of 10%. The marked price of the watch was:

The discount is on the marked price

A jacket marked ₹2,400 sold for ₹1,980 has a discount of 420 on 2400, 17.5%17.5\%. Dividing by 1980 gives 21.2%21.2\%, which no shop means.

Divide to undo a discount

A price of ₹960 after a 20%20\% discount comes from MP=960÷0.8=1200MP = 960 \div 0.8 = 1200. Adding 20%20\% to 960 gives 1152.

Concept 2 of 4: Successive discounts

The second discount is taken on the price left after the first, so the multipliers multiply. Two discounts together are always worth less than their sum.

Definition

  • Discounts of a%a\% then b%b\%: the buyer pays (1−a100)(1−b100)\left(1 - \tfrac{a}{100}\right)\left(1 - \tfrac{b}{100}\right) of the MP.
  • The single equivalent discount is a+b−ab100a + b - \dfrac{ab}{100} per cent.
  • The order of the discounts does not matter.
  • Three discounts: multiply three factors, or combine two at a time.

Single equivalent of two discounts

a+b−ab100a + b - \dfrac{ab}{100}

Worked example

Find the single discount equivalent to successive discounts of 25%25\% and 12%12\%.
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The same idea in a practice question:

Practice questionEasy

Example 2 · Profit and Loss · Marked Price and Discounts

What is the single equivalent discount for successive discounts of 20% and 10%?

Discounts do not add

25%25\% and 12%12\% together are 34%34\%, not 37%37\%: the 12%12\% is taken on a price already cut.

A rupee figure is a share of the marked price

If the equivalent discount comes to a rupee amount, that amount is the single percentage of the MP. Divide by the percentage, not by what the buyer paid.

Concept 3 of 4: Markup, then discount

Marking up by m%m\% multiplies the cost by 1+m1001 + \tfrac{m}{100}; the discount then multiplies by 1−d1001 - \tfrac{d}{100}. The profit is however much the product exceeds 1.

Definition

  • SP=CP(1+m100)(1−d100)SP = CP\left(1 + \tfrac{m}{100}\right)\left(1 - \tfrac{d}{100}\right).
  • Profit % =m−d−md100= m - d - \dfrac{md}{100}; a negative answer is a loss.
  • A markup and a discount of the same rate always lose: 20%20\% up and 20%20\% off leaves 0.96 of the cost.
  • To compare two discount plans on one MP, take the cost as 100 and work out each selling price.

Profit after a markup and a discount

Profit%=m−d−md100\text{Profit}\% = m - d - \dfrac{md}{100}

Worked example

A shopkeeper marks his goods 50%50\% above cost and allows a discount of 12%12\%. Find his profit per cent.
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The same idea in a practice question:

Practice questionEasy

Example 3 · Profit and Loss · Marked Price and Discounts

A trader marks his goods at 40% above the cost price and gives a discount of 10%. What is his profit percentage?

Subtracting the rates overstates the profit

50%50\% up and 12%12\% off is a profit of 32%32\%, not 38%38\%: the discount is taken on the raised price.

Same rate up and down is a loss

30%30\% up and 30%30\% off gives 1.3×0.7=0.911.3 \times 0.7 = 0.91 of the cost, a 9%9\% loss, not 'no profit, no loss'.

Concept 4 of 4: Marked price for a target profit

Work backwards from the cost. The target profit gives the selling price, and the discount says what fraction of the marked price that selling price is.

Definition

  • MP=CP×100+p100−dMP = CP \times \dfrac{100 + p}{100 - d}.
  • The markup needed is 100+p100−d−1\dfrac{100 + p}{100 - d} - 1.
  • From the MP back to the cost: CP=MP×100−d100+pCP = MP \times \dfrac{100 - d}{100 + p}.
  • Discount needed for a target profit: get the SP from the cost, then the discount is MP−SPMP\dfrac{MP - SP}{MP}.
  • A retailer who buys at a discount on the list price and sells at a smaller discount: his CP and SP are both shares of the list price.

Marked price for a target

MP=CP×100+p100−dMP = CP \times \dfrac{100 + p}{100 - d}

Worked example

A dealer wants a profit of 17%17\% after allowing a discount of 22%22\%. By what per cent above cost must he mark his goods?
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The same idea in a real exam question:

AFCAT · 2016 · AFCAT (I) 2016 — Numerical Ability · 02-212Easy

Example 4 · Profit and Loss · Marked Price and Discounts

A shopkeeper offers his customers a 10% discount and still makes a profit of 26%. What is the actual cost to him of an article marked ₹280?

Divide by the discount factor

A selling price of ₹612 after 15%15\% off means MP=612÷0.85=720MP = 612 \div 0.85 = 720. Multiplying by 1.15 gives 703.80.

The profit is on the cost, not on the marked price

A 20%20\% profit is 20%20\% of the cost. Taking it on the marked price gives a selling price that is too high.

Summary — formulas & gotchas at a glance

A revision cheat-sheet for the formulas and gotchas above. Click any concept name to jump back to its full explanation.

Formulas (4)

  • Discount on the marked price

    Selling price after a discount

    SP=MP(1−d100)SP = MP\left(1 - \dfrac{d}{100}\right)
  • Successive discounts

    Single equivalent of two discounts

    a+b−ab100a + b - \dfrac{ab}{100}
  • Markup, then discount

    Profit after a markup and a discount

    Profit%=m−d−md100\text{Profit}\% = m - d - \dfrac{md}{100}
  • Marked price for a target profit

    Marked price for a target

    MP=CP×100+p100−dMP = CP \times \dfrac{100 + p}{100 - d}

Watch out for (8)

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